Volcanoes Volcanoes and Plate Tectonics Properties of Magma Volcanic Eruptions Volcanic Landforms Table of Contents.

Volcanoes

Volcanoes and Plate Tectonics

Properties of Magma

Volcanic Eruptions

Volcanic Landforms

Table of Contents

Volcanoes

Volcanoes and Plate Tectonics

1. What is a volcano?

It is a weak spot in the crust where molten material, or magma, comes to the surface.

2. A molten mix of rock-forming substances, gases, and water from the mantle is referred to as ____.

Magma

3. When magma reaches the surface, it is called ______.

Lava

Volcanoes - Volcanoes and Plate Tectonics

Many of Earth’s volcanoes are located along the boundaries of tectonic plates. The Ring of Fire is a belt of volcanoes that circles the Pacific Ocean.

What other regions have a large number of volcanoes?

Volcanoes

Volcanoes and Plate Tectonics

4. What is the Ring of Fire?

It is a major volcanic belt formed by the many volcanoes that rim the Pacific Ocean.

5. Where do most volcanoes form?

They form along diverging plate boundaries such as mid-ocean ridges and along converging plate boundaries where subduction takes place.

Volcanoes

Volcanoes and Plate Tectonics6. Describe how volcanoes form along the mid-ocean

ridges.

Along the rift valley, lava pours out of cracks in the ocean floor, gradually building new mountains.

7. Volcanoes can form along diverging plate boundaries on land.

True

8. Many volcanoes form near converging plate boundaries where oceanic crust returns to the mantle.

True

Volcanoes

Volcanoes and Plate Tectonics

9. How does subduction at converging plate boundaries lead to the formation of volcanoes?

When the older, denser plate sinks beneath a deep-ocean trench into the mantle, some of the rock above the subducting plate melts and forms magma. Because the magma is less dense than the surrounding rock it rises toward the surface. Eventually, the magma breaks through the ocean floor, creating volcanoes

Volcanoes

Volcanoes and Plate Tectonics

*** Volcanoes can also form where oceanic crust is subducted beneath continental crust.

10. Volcanoes at boundaries where two oceanic plates collide create a string of islands called an ______.

Island arc

Volcanoes

Volcanoes and Plate Tectonics

11. What are three major island arcs?

They are Japan, New Zealand, Indonesia, the Philippines, the Aleutians, the Caribbean Islands

12.Types of plates that collide to form the Andes Mountain on the west coast of South America.

* A continental plate and an ocean plate

Volcanoes - Volcanoes and Plate Tectonics

Volcanoes often form where two oceanic plates collide or where an oceanic plate collides with a continental plate. In both situations, an oceanic plate sinks beneath a trench. Rock above the plate melts to form magma, which then erupts to the surface as lava.

Volcanoes at converging boundaries

Volcanoes - Volcanoes and Plate Tectonics

Hot Spot Volcanoes: Eventually, the Pacific plate’s movements will carry the island of Hawaii away from the hot spot. Which island on the map formed first?

Volcanoes

Volcanoes and Plate Tectonics

13.What is a hot spot?

It is an area where material from within the mantle rises and melts, forming magma.

14. How did the Hawaiian Islands form?

They formed over millions of years as the Pacific plate drifted over a hot spot.

15. Hot spots form only under oceanic crust.

False

Volcanoes

End of Section:Volcanoes and Plate Tectonics

Volcanoes

Properties of Magma

Main Idea

Magma’s viscosity depends on…

Detail: Magma is made of elements and compounds, among them silica.

Detail: Viscosity is a property of magma.

Detail: Viscosity depends on silica content and temperature.

Volcanoes

Properties of Magma

1. A substance cannot be broken down into other substances is called an _____.

Element

2. When frozen water melts, it is undergoing a physical change.

True

3. Statements that indicate a chemical property.• When paper is burned, it forms ashes.• An iron chair will develop rust if oxygen

combines with the iron.

Volcanoes

Properties of Magma

4. The greater the viscosity, the _____ a liquid flows. The ______ the viscosity, the more easily a liquid flows.

Slower

Lower

5. Liquids that can have a low viscosity.

• Milk

• Orange Juice

6. What two factors determine the viscosity of magma?

Temperature and silica content

Volcanoes

Properties of Magma

7. Statement that are true about silica.• Silica makes magma thicker.• Silica produces a light colored lava.

8. The rock ______ forms from light-colored lava.

Rhyolite

9. Low-silica magma forms rocks like ____.

Basalt

Volcanoes - Properties of Magma

What type of magma would have a higher viscosity? Explain:

Volcanoes

Properties of Magma

Lava_on_Land_and_in_Water.asf

Volcanoes

Properties of Magma

10.What happens to the viscosity as temperature increases?

It decreases.

11. Hot fast moving lava is called ____.

pa hoe hoe

12. Cool, slow moving lava is called ____.

a a

Volcanoes

Properties of Magma

13.Chart:

High viscosity Magma is usually lower in temperature and/or has a higher silica content. Low viscosity magma usually has a higher temperature and/or a lower silica content.

A. Low

B. Lower

C. Higher

D. Lower

Volcanoes

Properties of Magma

13. e.

State the relationship between temperature and silica content in magmas that have high viscosity and magmas that have low viscosity.

The lower the temperature and the higher the silica content of magma, the higher the viscosity. The higher the temperature and the lower the silica content of magma, the lower the viscosity of the magma.

Volcanoes

End of Section:Properties of

Magma

Volcanoes

Volcanic Eruptions

What You Know

1.Lava flows out of a volcano.

2.Eruptions are not all the same.

3.Some volcanoes are dormant.

Volcanoes

Volcanic Eruptions

1. Magma forms in the lithosphere.

False-- asthenosphere

2. Liquid magma rises until it reaches the surface, or until it becomes trapped beneath layers of rock.

True

3. Features that all volcanoes share.

A pocket of magma beneath the surface

A crack at the surface

Volcanoes - Volcanic Eruptions

4. A volcano forms where magma breaks through the Earth’s crust and lava flows over the surface.

a. Pipeb. Craterc. Ventd. Magma chamber

Volcanoes

Volcanic Eruptions5. What is a lava flow?

It is the area covered by lava as it pours out of a vent.

6. Where does a crater form?

At the top of the volcano around the central vent.

7. The pipe of a volcano is a horizontal crack in the crust.

False – it is a long tube in the ground that connects the magma chamber to the Earth’s surface.

Volcanoes

Volcanic Eruptions

8. Complete the flowchart about how magma moves through a volcano.

Lava flow

a.Crater

b.Vent

c.Pipe

d.Magma chamber

e. What does the graph show about where magma goes after it leaves the pipes?

It goes to the vent.

Volcanoes

Volcanic Eruptions

9. Sentences that describe the best model of a volcano erupting.

•Carbon dioxide dissolved in soda pop rushing out when a soda pop is opened.

10. What happens during a volcanic eruption?

The force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent.

Volcanoes

Volcanic Eruptions

11. What factors determine the force of a volcanic eruption?

The main factors are the magma’s silica content and viscosity.

12. A volcano erupts quietly if it’s magma is thick and sticky.

False -- explosively

13.Volcanic ash:

C- is made up of fine particles as small as a grain of sand.

Volcanoes

Volcanic Eruptions

14. Cinders:

A- are pebble-sized particles.

15. Bombs:

B- are particles ranging from the size of a baseball to the size of a car.

16. What is a pyroclastic flow?

It is an explosive eruption that hurls out a mixture of hot gases, ash, cinders, and bombs.

Volcanoes

Volcanic Eruptions

17. Volcanic eruptions cause damage only when they are close to the crater’s rim.

False

18. What kinds of damage can volcanoes cause?

Volcanic ash can bury entire towns. If it becomes wet, the heavy ash can cause roofs to collapse. Eruptions can cause landslides and avalanches of mud, melted snow and, rock.

Volcanoes

Volcanic Eruptions\

19.The activity of a volcano may last from less than a decade to more than 10 million years.

True

20.Most long-lived volcanoes erupt

continuously.

False

Volcanoes

Volcanic Eruptions21. Complete the compare/contrast table.

a. An extinct volcano is very unlikely to erupt ever again.

b. An active volcano is erupting or showing signs that it will soon erupt.

c. A dormant volcano is no longer active, but may become active again.

d. Rank the volcanic stages from least likely to erupt to most likely to erupt:

extinct, dormant, active

Volcanoes - Volcanic Eruptions

Within the last 150 years major volcanic eruptions have greatly affected the land and people around them.

Volcanoes

Volcanic Eruptions22. The length of time between eruptions of a dormant volcano is

always less than a thousand years.

False– it is unknown

23. Why might people living near a dormant volcano may be unaware of the danger?

The time between volcanic eruptions may span hundreds to many thousands of years.

24. Sentences true about predicting volcanic eruptions.• Geologists are more successful in predicting volcanic

eruptions than earthquakes.• Geologists cannot predict what type of eruption a volcano will

produce.

Volcanoes

End of Section:Volcanic Eruptions

Volcanoes

Volcanic Landforms

I. Landforms From Lava and Ash

A. Shield Volcanoes

B. Cinder Cone Volcanoes

C. Composite Volcanoes

D. Lava Plateaus

E. Calderas

F. Soils from Lava and Ash

Volcanoes

Volcanic Landforms

II. Landforms from Magma

A. Volcanic necks

B. Dikes and Sills

C. Batholiths

D. Dome Mountains

III. Geothermal Activity

A. Hot Springs

B. Geysers

C. Geothermal Energy

Volcanoes - Volcanic Landforms

Volcanic activity is responsible for forming lava plateaus.

Volcanoes

Volcanic Landforms1. List four landforms created from lava and ash.

a. shield volcanoes

b. cinder cone volcanoes

c. composite volcanoes

d. lava plateaus

2. Sentences true about shield volcanoes.

• They form from many thin layers of lava.

• They result from quiet eruptions.

3. The Hawaiian Islands are cinder cone volcanoes.

False – shield volcanoes

Volcanoes

Volcanic Landforms

4. Name two examples of composite volcanoes.• Mount Fuji in Japan • Mount St. Helens in Washington State.

5. A composite volcano has both quiet and explosive eruptions.

True

6. Shield volcano:

E- is a gently sloping mountain formed by repeated lava flows.

Volcanoes

Volcanic Landforms

7. Cinder cone volcanoes:

C- Cone-shaped mountains formed from ash, cinders, and bombs were once.

8. Composite volcano:

B- A mountain formed by lava flows alternating with explosive eruptions is a.

9. Lava plateau:

A- is a high, level area formed by repeated lava flows.

Volcanoes

10. Caldera:

D- is a hole left by the collapse of a volcanic mountain.

11. When volcanic ash breaks down, it releases _____ and, _____ both of which are needed by plants.

Potassium

Phosphorus

Volcanoes

Volcanic Landforms

12.List five features formed by magma.

a. volcanic necks

b. dikes

c. sills

d. batholiths

e. dome mountains

Volcanoes - Volcanic Landforms

1 The top of a composite volcano explodes. Lava flows partially empty the magma chamber.

2 The roof of the magma chamber collapses, forming a caldera

Volcanoes - Volcanic Landforms

Magma that hardens beneath the surface may form volcanic necks, dikes, and sills. A dike extends outward from Ship Rock, a volcanic neck in New Mexico.

What is the difference between a dike and a sill?

Volcanoes

Volcanic Landforms13. Complete the Venn Diagram:• A dike forms across rock layers.• A sill forms between rock layers.• Both a dike and a sill forms from magma.

14. A mass of rock formed when a large body of magma cools inside the crust is called a ______.

Batholith

15. What is an example of a batholith in the United States?

The Sierra Nevada Mountains in California.

Volcanoes - Volcanic Landforms

BatholithsSeveral large batholiths form the core of mountain ranges in western North America. Half Dome in Yosemite National Park, California is part of the Sierra Nevada batholith.

Volcanoes

Volcanic Landforms

16. A dome mountain forms when rising magma is blocked by horizontal layers of rock.

True

17. Some types of volcanic activity do not involve the eruption of lava.

True

18. When groundwater is heated by a nearby body of magma rises to the surface and collects in a natural pool, it is called a ____.

Hot springs

Volcanoes

Volcanic Landforms

19. A fountain of water and steam that erupts from the ground is referred to as a ____.

Geyser

20. How can geothermal energy be converted to electricity?

Steam from underground is piped into turbines. Inside a turbine, the steam spins a wheel. The moving wheel in the turbine turns a generator that turns mechanical energy into electrical energy.

Volcanoes

Volcanic Landforms

• Key Terms:1. Magma

2. Crater

3. Silica

4. Pahoehoe

5. Aa

6. Geyser

7. Volcano

8. Lava

9. Active

10.Caldera

11.Extinct

12.Batholith

13.Dike

14.Sills

Volcanoes

End of Section:Volcanic

Landforms